In a conventional method of manufacturing a sintered product, a molded product is formed by injection molding of a metal or ceramic powder and then sintered to form the sintered product. Generally, in injection molding of a metal or ceramic powder, a plastic molding composition is prepared by mixing the powder with a large amount of binder resin (binding agent) and used. In this case, in order to pour the composition in a molding die, the composition is heated to a temperature of, for example, 200° C. It is noted that when the binder resin is used, the sintered product is broken if the molded product is sintered directly. Therefore, a degreasing process, in which the molded product is heated to a temperature of from 500° C. to 600° C. to decompose the binder resin, needs to be performed before the molded product is sintered.
U.S. Pat. No. 4,734,237 corresponding to JP-B-2,604,592 discloses using a small amount of agar and water as a binder instead of binder resin. This approach can allow the composition to have flowability by heating the composition to a temperature of 80° C. to 100° C. Further, since the amount of the binder contained in the molded product is small, the degreasing process can become unnecessary.